First a word about commercial heat gear. It's good stuff, They usually uses a lot of watts, (something that motos aren't known for a lot of), and together with a heat controller work quite well with not much effort or thought per ride.
...........once you've located a good method of mounting the HC. Also don't forget that using a lot of watts with the commercial gear doesn't leave you much for auxiliary Light, hand heaters, and leg and foot heat.
If you're bike is watt challenged, you can still have all the accessories by making gear that is/are watts frugal.
For instance the red jacket heat liner above isn't nearly as watts efficient as the white heat shirt above. The jacket liner is away from the body, but, in it's defense, it's easy to throw that jacket on to go for a ride if the days not too cold....and you won't be out at night when you might be using your extra driving lights, and on and on.
The shirt can be used closer to your body where the heat does the most good, and extra insulation (like an extra shirt on top, only makes it better. For making the most use of the heat, you wear it on top of your Undershirt. You'd prolly need a HC for that. Remember that you can build whatever you want if the heat shirt is too hot....add a little extra wire to the next one.
You have to be 2 things to make your own gear. You need to be a tinkerer, and you have to realize that you can't buy what you really want.
Once you've developed the skills and knowledge to make heat gear, for another 10 dollars and an afternoon, you can whip up another new idea to try out on your next ride.
I've probably made 10 pieces of heat gear. The first 5 weren't robust enough physically. Like for instance I used solid wire for the first one. The wire kinked and broke. It took me a while to learn how to splice small
wire and make the connector connections.
All these teething issues are what I'm trying to save you from. I hope this help someone. And I freely admit that I won't make my next shirt like I made the last one, and my methods aren't the best way. I just documented them here to give you all more ideas to start with.
While I'm making this post let me give you a couple pictures of my hot water heater for coffee, soup, dried food, or....
I started out with a 1 Qt thermos (thrift store), and added some wire (enough to use 10 amps of juice)
That's 26 ga wire and about 40 ft of it....The lead in wire has to be long enough to get into the liquid. Takes about 30 minute of riding to boil 2 cups of water.